Shimla to Narkanda-Rampur Bushahr-Powari-Pooh-Dubling village drive is on National Highway 5 (NH5). The Dubling village to Nako-Tabo-Kaza drive is on NH505. Kaza is the headquarters of Spiti valley. During winters, Shimla-Narkanda-Rampur road gets closed for a day or two whenever there is a long spell of snowfall. During such events, take the Shimla-Suni-Rampur Bushahr route along the Satluj river. This route stays open for all 365 days of the year.
It takes longer — when compared from Manali to Spiti valley (Via Atal tunnel) route — to reach Kaza from Shimla.
Shimla is one of the two places (second is Manali town) to start the Spiti valley circuit tour.